Mechanical strength of connection of wound rotor generator/motor

ABSTRACT

A rotor of a wound rotor motor/generator comprising a plurality of rotor windings including a line rotor coil and a star rotor coil. The rotor coil couples to an L-conductor having an L-shaped profile such that a portion of the L-conductor extends from the line rotor coil toward the star rotor coil. A line connector bar couples the L-conductor to a rotor lead such that the line rotor coil is electrically coupled to the rotor lead. The star rotor coil couples to an L-support having an L-shaped profile such that a portion of the L-support extends from the star rotor coil toward the line rotor coil. An insulator is positioned between the L-conductor and the L-support to electrically insulate the L-support from the L-conductor. Lastly, an insulating rope couples the L-conductor to the L-support.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to co-pendingU.S. Pat. Application No. 17/693,195, filed on Mar. 11, 2022, whichclaims the benefit of U.S. Provisional Pat. Application No. 63/161,667,filed on Mar. 16, 2021, the entire contents of each of which areincorporated by reference herein.

BACKGROUND

The present application relates to wound rotor generators and woundrotor motors and, more particularly, to the connections of the woundrotor generator/motor. Some aspects of the invention relate particularlyto wind turbine generator rotor construction and/or refurbishment.

SUMMARY

In one aspect, the invention provides a rotor of a wound rotormotor/generator comprising a plurality of rotor windings including aline rotor coil and a star rotor coil. The rotor coil couples to anL-conductor having an L-shaped profile such that a portion of theL-conductor extends from the line rotor coil toward the star rotor coil.A line connector bar couples the L-conductor to a rotor lead such thatthe line rotor coil is electrically coupled to the rotor lead. The starrotor coil couples to an L-support having an L-shaped profile such thata portion of the L-support extends from the star rotor coil toward theline rotor coil. An insulator is positioned between the L-conductor andthe L-support to electrically insulate the L-support from theL-conductor. Lastly, an insulating rope couples the L-conductor to theL-support.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a non-connection end of a diamond coilrotor.

FIG. 2 is a perspective view a connection end of the diamond coil rotor.

FIG. 3 is a perspective view of an embodiment of top and bottom coils.

FIG. 4 is a perspective view of the top and bottom coils shown in FIG. 3with a connection end, non-connection end, and core section.

FIG. 5 is a perspective view of a non-connection end of a rotor havingthe top and bottom coils shown in FIG. 3 .

FIG. 6 is a partial perspective view of a connection end of a rotorhaving the top and bottom coils shown in FIG. 3 .

FIG. 7 is a perspective view of the connection end having extendedspacer blocks between connections.

FIG. 8 is a perspective view of the connection end having insulatingrope.

FIG. 9 is a perspective view of the connection end having a crossconnection assembly formed of dual L-connectors located on a crossconnection ring.

FIG. 10 is a perspective view of the cross connection assembly.

FIG. 11 is a perspective view of the connection end having a pluralityof cross connection assemblies.

FIG. 12 is a perspective view of the connection end having a starconnection assembly formed of dual L-connectors mounted onto a starconnection ring.

FIG. 13 is a perspective view of the star connection assembly.

FIG. 14 is a perspective view of a connection between the line rotorcoil ends and rotor leads at the connection end, the connection havingan L-conductor and a line connection bar.

FIG. 15 is a perspective view of the connection shown in FIG. 14 with anL-support.

FIG. 16 is a perspective view of the connection shown in FIG. 15 withinsulating rope around the L-conductor and L-support.

FIG. 17 is a perspective view of the L-conductor or L-support havingflat bottom holes.

FIG. 18 is a perspective view of the connection end having theL-conductors and L-supports and additional mechanical supports.

FIG. 19 is a perspective view of the connection end illustrating aconnection between the line connector bar and a support ring.

FIG. 20 is a perspective view of the connection between the lineconnector bar and the rotor lead.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways.

FIGS. 1 and 2 illustrate a rotor 10 of a wound rotor generator/motor 14,also referred to as a slip ring induction generator/motor. A wound rotorgenerator/motor 14 is an induction machine having rotor windings 18 thatare connected through slip rings to external resistance or power source.A speed/torque characteristic of the motor is controllable by modifyingthe external resistance. If an external power source is connected to theslip rings, the generator can be used to generate different/specificoutput frequencies - typically used in wind generators.

In comparison to a squirrel-cage rotor, which is another example of aninduction motor, the rotor 10 of the wound rotor generator/motor 14 hasmore winding turns such that the induced voltage is higher, and thecurrent is lower. The wound rotor motor 14 also has a higher startingtorque. During the start-up, the rotor 10 has three poles connected tothe slip ring with each pole wired in series with a variable powerresistor. When the motor 14 reaches full speed the rotor poles areswitched to short circuit. During start-up the resistors reduce thefield strength at the stator, resulting in a reduced inrush current.

In a traditional wound rotor motor/generator such as the one shown inFIGS. 1 and 2 , the rotor coils 18 and the structures that electricallyand physically couple the rotor coils 18 to the rotor leads may bepoints of structural failure in the face of fatigue stress from normaluse, leading to the need to repair or replace the rotor 10. Although therotor 10 can be refurbished or replaced back to original specification,similar limited service life may be expected. On the other hand, therotor 34 shown in FIGS. 3-20 includes improvements that maysignificantly increase the service life of a wound rotormotor/generator. Although not necessarily limited, the rotor 34 of FIGS.3-20 can be a refurbishment or retrofit of components onto apre-existing rotor like the rotor 10 of FIGS. 1-2 , which may havefailed in service. For example, the rotor coils 18 may be removed fromthe rotor core 12 of the failed rotor 10 and replaced entirely withcomponents according to the design of the rotor the followingdescription. Aspects of the illustrated rotor 34 may also be used in theconstruction of an original, previously unused apparatus.

FIGS. 3-20 illustrate the rotor 34 of a wound rotor generator/motor invarious states of assembly with various components shown or removed forclarity. Even where shown and described separately, features of FIGS.3-20 are understood to be useful as solitary improvements, useful invarious combinations with each other, or useful all together in theconstruction of the rotor 34 of the wound rotor generator/motor.

The rotor windings 38 shown in FIG. 3 have a half bar design, deviatingfrom the diamond coil design shown in FIGS. 1-2 . This half bar designsplits the winding into two separate bars - a top coil 42 and a bottomcoil 46. The top coil 42 is positioned radially outward relative to thebottom coil 46 such that top coil 42 may otherwise be referred to as aradially outer coil and the bottom coil 46 may be referred to as aradially inner coil. Each of the top coil 42 and the bottom coil 46 havea substantially uniform rectangular cross-section along a length of therespective coil 42, 46. The profile of the cross-section can bedescribed as a flat profile, as one of the rectangular dimensions may beat least 3, at least 4, or at least 5 times the other rectangulardimension. As shown in FIGS. 5-6 for example, the small dimension isarranged circumferentially to facilitate fitting the winding 38 into thecorresponding rotor core slots. The larger rectangular dimension extendsradially on the rotor. With respect to FIG. 4 , each coil 42, 46includes a central portion referred to as the core section 50, anon-connection end 54 extending from one end of the core section 50, anda connection end 58 extending from the other end of the core section 50.As shown in FIGS. 3-6 , the core section 50 extends linearly, and theconnection and non-connection ends 54, 58 extend at an angle from thecore section 50. In some embodiments, the angle between the ends 54, 58and the core portion 50 is a complex angle such that the opposing topand bottom coils 42, 46 align with one another when assembled atnon-radially opposed positions.

FIG. 5 illustrates the non-connection ends 54 of installed top andbottom coils 42, 46 of two separate windings 38. The top and bottomcoils of a first winding are labeled 42-1, 46-1. The top and bottomcoils of a second winding are labeled 42-2, 46-2. For the sake ofclarity in the drawing, the coils of only two windings 38 are shown. Thedistal end (opposite the core section) of each coil’s non-connection end54 includes a bent end portion 62 that has a flat profile and is angledrelative to the remainder of the respective winding’s non-connection end54. As such, installation of the top and bottom coils 42-1, 46-1 of thefirst winding positions the flat end portions 62 alongside and inalignment with each other as shown in FIG. 5 . Particularly, therespective flat end portions 62 are co-planar and aligned or stacked inthe radial direction. In this arrangement, the top and bottom coils42-1, 46-1 of the winding can be joined (e.g., soldered, brazed, orwelded to form a joint 56, FIG. 4 ) to one another at the non-connectionends 54 to establish electrical continuity throughout the winding. Forthe second and each additional winding 38, a similar construction isprovided whereby the winding’s top and bottom coils (e.g., 42-2, 46-2 ofsecond winding) are positioned and joined together in accordance withthe preceding description.

At the opposite end of the rotor 34, the connection ends 58 of the topand bottom coils 42, 46 likewise include, at a distal end (opposite thecore section), a bent end portion 66 that has a flat profile and isangled relative to the remainder of the respective winding’s connectionend 58. However, instead of the top and bottom coils 42-1, 46-1 of thefirst winding having their flat end portions 66 aligned, the top coil42-1 of a first one of the windings 38 is positioned alongside and inalignment with the bottom coil 46-2 of an adjacent one of the windings38 as shown in FIG. 6 . The adjacent windings occupy successive oradjacent rotor core slots as shown. The positioning between the top andbottom coils 42-1, 46-2 of the adjacent windings can be co-planar andaligned or stacked in the radial direction. In this arrangement, the topand bottom coils 42-1, 46-2 can be joined (e.g., soldered, brazed, orwelded to form a joint 68) to adjacent coils 42, 46 at the connectionends 58. This construction between each successive pair of windings 38,only two of which are shown in FIG. 6 , is repeated in all of the rotorslots around the circumference of the rotor 34.

The half bar design can improve the manufacture and installation,thereby reducing labor time and lead times for delivery, despite thatthere are two windings 38 for each rotor slot rather than one windingper slot. Splitting the conductor for each rotor slot into multipleparallel sections reduces the mechanical force required to bend eachcoil 42, 46. Additionally, all top coils 42 are interchangeable suchthat a failure of a top coil 42 (e.g., during process testing), the topcoil 42 can be swapped out with a new top coil 42 without removing orreplacing any of the bottom coils 46 or any of the other top coils 42.The bottom coils 46 are likewise interchangeable having similaradvantages as the top coils 42 as described herein.

As shown in FIG. 7 , extended spacer blocks 74 are positioned betweenbottom coils 46 at the connection end 58. The extended spacer blocks 74extend radially inwardly such that they protrude past the end of thecoils 46 to a position located radially inward of the bottom coils 74.The extended spacer blocks 74 are manufactured from a glass mat orlaminate saturated and cured with polyester resin or epoxy resin. Thedistance between each block is less than or equal to 2 inches. Forexample, if the inner diameter of the blocks is 30 inches, thecircumference is therefore approximately 94.2 inches, such that 48 totalblocks (94.2/2 rounded up) is the minimum required number of blocks tomaintain the 2- maximum distance between blocks. As shown, the blocks 74are tapered to fit snug between adjacent connection clips 70. The spacerblocks 74 are utilized to mechanically retain insulating glass rope 78as shown in FIG. 8 and discussed in greater detail below. Dimensionsgiven above can be representative of a 3 MW generator, for example, thatof the V-90 design of Vestas Wind Systems of Denmark.

FIG. 8 illustrates several rows of insulating rope 78 installed relativeto the spacer blocks 74. The insulating rope 78 spaces conductorcomponents relative to one another. Additionally, the rope 78mechanically retains, secures, and insulates the conductor components.In some embodiments, the insulating rope 78 is a bundle of glass fiberrovings encased in a braided fiberglass sleeving. In alternativeembodiments, the insulating rope 78 may be, for example, tadpole tape, adense fiberglass rope, or a low-density fiberglass rope. Someembodiments may use different ropes based on the available space for therope. The insulating rope 78 may have a circular cross-section having adiameter of, for example, ¼”, ½”, ¾”, or 1″. Alternatively, theinsulating rope may have a rectangular cross-section having, forexample, a width of 1″ and a height of ¼”. The insulating rope 78 may beheat resistant to high temperatures (e.g., greater than 900° F.) in viewof the relatively high temperatures reached within the motor based on,for example, run time, speed of the motor, and ambient temperature.

Prior to impregnating the insulating rope 78 with resin (polyester,epoxy, silicone), the insulating rope 78 is compressible (e.g.,compressible by 33%, compressible by 50%) such that the insulating ropeis oversized for the available space (e.g., sized to 150% of theavailable space), thereby permitting good compression and a snug fit ofthe insulating rope 78 within the available space.

As shown in FIG. 8 , the insulating rope 78 is installed at variouslocations. At reference numeral 2, the insulating rope 78 is positionedaxially between the extended spacer blocks 74 and a first crossconnection assembly 110 at a location below (i.e., radially inward from)the bottom coil 46. At reference numeral 3, the insulating rope 78 ispositioned axially between the first cross connection assembly 110 and asecond cross connection assembly 114 at a location below the bottom coil46. At reference numeral 4, the insulating rope 78 is located on top ofthe second cross connection assembly 110 at a location below the bottomcoil 46. At reference numerals 5 and 6, the insulating ropes 78 arepositioned on top of the bottom coil 46 and below the top coil 42 at alocation below the first cross connection assembly 110. At referencenumeral 7, the insulating rope 78 is located on top of the bottom coil46 and below the top coil 42. At reference numeral 8, the insulatingrope 78 is positioned on top of the bottom coil 46 and below the topcoil 42 at a location next to a star connection assembly 118. Atreference numeral 9, the insulating rope 78 is positioned on top of thestar connection assembly 118 and below the top coil 42. The quantity ofinsulating ropes 78 may be increased depending on the specificconfiguration and widths of the first and second cross connectionassemblies 110, 114 and the star connection assembly 118. The crossconnection assemblies 110, 114 and star connection assembly 118 arediscussed in greater detail below.

FIG. 9 illustrates two L-shaped connectors 82, 86 that connect the crossconnection ring 98 to the coil ends to form the cross connections of thewindings 38. As shown, each L-connector 82, 86 has a height along afirst portion 90a, 90b, a radial portion, that extends across the entireheight of the bottom coil 46. A second portion 94a, 94b of eachL-connector 82, 86, a circumferential portion, extends transverse to thefirst portion 92a, 92b and rests upon the cross connection ring 98. Asthe cross connection ring 98 is arcuate, the second portion 94a, 94b ofeach L-connector 82, 86 may be likewise arcuate, shaped to fit adjacentto the outer diameter of the cross connection ring 98. The L-connector82, 86 is formed as a unitary, bent component such that the transitionbetween the first portion 92a, 92b and the second portion 94a, 94bincludes a radius.

The dual L-connectors 82, 86 are mounted back-to-back, sandwiching thebottom coil 46 therebetween, in the circumferential direction, such thatthe first portions 92a, 92b of the dual L-connectors 82, 86 are parallelto one another and abut opposing sides of the bottom coil 46.Additionally, the second portions 94a, 94b extend away from the bottomcoil 46 and from one another along the circumference of the crossconnection ring 98. As shown, the lengths of the second portions 94a,94b of the L-connectors 82, 86 may differ in order to provide space forfitment of other parts.

A filler spacer 130 is positioned between the bottom coil 46 and thecross connection ring 98 to fill the gap formed between the crossconnection ring 98, the bottom coil 46, and the dual L-connectors 82,86. The placement of the filler spacer 130 maintains a gap between thecross connection ring 98 and the bottom coil 46 for the insulating rope78 shown in FIG. 8 at reference numerals 2, 3, and 4.

Multiple sets of the dual L-connectors 82, 86 are secured (e.g., brazed,soldered, welded) to both ends of the cross connection rings 98 to formcross connection assemblies 110, as shown in FIG. 10 . As shown in FIG.11 , several cross connection assemblies 110 are used in combinationwith one another on a single rotor assembly. As shown, three of thecross connection assemblies 110 are considered back cross connectionassemblies and the other three cross connection assemblies 114 areconsidered front cross connection assemblies. The back cross connectionassemblies 110 are those that are nearest to the core and the frontcross connection assemblies 114 are those that are furthest from thecore. The front and rear cross connection assemblies 110, 114 each formnearly full circles, with gaps 138 (e.g., 5-10 degree gaps) between eachassembly 110, 114. Accordingly, the cross connection rings 98 may beconsidered arcuate ring segments, rather than full rings. The front andrear cross connection assemblies 110, 114 are coaxial with one anotherand have substantially similar diameters such that they are effectivelystacked axially on each other. The gaps 138 between adjacent front crossconnection assemblies 114 are offset are rotationally offset (e.g., by45 degrees) from the gaps 138 between adjacent back cross connectionassemblies 114.

FIGS. 12-13 illustrate multiple dual L-connectors 146, 150 mounted to astar connection ring 154 to form the star connection assembly 118. Thedual L-connectors 146, 150 are substantially similar to the dualL-connectors 82, 86 shown in FIGS. 10-11 with respect to the crossconnection ring 98. The dual L-connectors 82, 86 are mounted to the starconnection ring 154 in a similar back-to-back manner, sandwiching thetop coil 42 therebetween. A filler spacer 158 is positioned between thebottom of the top coil 42 and the outside diameter of the starconnection ring 154 between the dual L-connectors 146, 150. As shown inFIG. 13 , multiple sets of the dual L-connectors 146, 150 are secured(e.g., brazed, soldered, welded) onto the outside diameter of the starconnection ring 154 to form the star connection assembly 118.

FIGS. 14-20 illustrate a line rotor coil connection to the rotor lead166 at the connection end 58. FIG. 14 illustrates the line rotor coil170, and an L-conductor 174 and rectangular line connector bar 178 thatconnect the end of the line rotor coil 170 to the rotor leads 166. Afirst portion 182, an axial portion, of the L-conductor 174 is incontact with the end of the line coil 170. A second portion 186 of theL-conductor 174, a circumferential portion, extends transverse (e.g., ina perpendicular plane) with respect to the first portion 182 such thatthe first and second portions 182, 186 define an L-shape. The secondportion 186 extends away from the line coil 170 and towards an adjacentend of a star rotor coil 190. An outer edge 194 (nearer the outerdiameter of the rotor 34) of the second portion 186 of the L-conductor174 is a curved edge following a smaller radius away from the firstportion 182 to create a shoulder 198 and to allow for fitment ofinsulating rope 246, as shown in FIG. 16 and described in greater detailbelow. While the shoulder 198 and curved surface are shown on theradially outer edge, they may otherwise or additionally be located onthe radially inner edge of the L-conductor 174.

With continued reference to FIG. 14 , the line connector bar 178 has arectangular cross-section and is secured (e.g., brazed, soldered,welded) at a radially outer end 210 to the L-conductor 174. A radiallyinner end 214 is secured to the rotor lead 166, as described in greaterdetail below with respect to FIG. 20 . As the L-conductor 174 and theline conductor bar 178 both carry current, they are formed in someembodiments from copper. In other embodiments, one or both of theL-conductor 174 and the line connector bar 178 may be otherwisemanufactured from other copper alloys such as brass, bronze, chromecopper zirconium (CuCrZr), or beryllium copper (CuBe).

FIG. 15 illustrates that the end of the star rotor coil 190 has anL-support 222 that is aligned axially with the second portion 186 of theline coil L-conductor 174. The L-support 222 is manufactured from a highmechanical strength copper alloy such as brass, bronze, chrome copperzirconium (CuCrZr), or beryllium copper (CuBe) and is sized and shapedsimilar to the L-conductor 174. More specifically, the L-support 222includes a first portion 226, an axial portion, that is secured (e.g.,brazed, soldered, welded) to the end of the star coil 190 such that thelength of the first portion 226 (between a distal end and a secondportion 230 of the L-support 222) abuts the end of the star coil 190.The second portion 230 of the L-support 222, a circumferential portion,extends transverse (e.g., in a perpendicular plane) with respect to thefirst portion 226 such that the first and second portions 226, 230define an L-shape. The second portion 230 extends away from the starrotor coil 190 and towards an adjacent end of a line rotor coil 170 towhich the L-conductor 174 is affixed. The distal end of the firstportion 226 of the L-support 222 is located nearer to the end of thestar rotor coil 190 such that the second portion 230 of the L-support222 is located axially inward of the first portion 226 of the L-support222. In contrast, the L-conductor 174 is arranged in an opposite manner,with the distal end of the first portion 182 of the L-conductor 174being located axially inward of the second portion 186 of theL-conductor 174. In this way, the L-conductor 174 and L-support 222 arenested relative to one another with the second portions 186, 230 of therespective L-support 174 and L-conductor 222 being aligned axially(common or overlapping axial position) with the first portion 226, 182of the other.

The second portion 230 of the L-support 222 is parallel to and spacedapart axially from the second portion 186 of the L-conductor 174. Aninsulator 238 is positioned axially between the second portions 186, 230of the L-conductor 174 and the L-support 222 to physically space andelectrically insulate the second portions 186, 230 from one another. Theinsulator 238 may be constructed of a felt material. In otherembodiments, the insulator 238 may be made from a rigid material such asa GP03 glass mat with polyester resin or a G10 glass laminate with epoxyresin. As shown, the insulator 238 is sized and shaped to follow theoverlapping shape of the two second portions 186, 230.

FIG. 16 illustrates rectangular support blocks 242 connected to theL-conductor 174 and the L-support 222 to facilitate the winding of theinsulating rope 246 around the L-conductor 174 and the L-support 222. Asshown, the rectangular blocks 242 are secured (e.g., brazed, soldered,welded) to the axially outer surface of the L-conductor 174. Althoughnot shown, similar rectangular blocks are also secured to the axiallyinner surface of the L-support 222 (i.e., the blocks are provided onopposing surfaces of the L-conductor 174 and the L-support 222 that faceaway from one another). The support blocks 242 can be manufactured fromcopper though may be otherwise manufactured from a copper alloy such asbrass, bronze, chrome copper zirconium (CuCrZr), or beryllium copper(CuBe). The blocks 242 are spaced equidistant from one another orotherwise spaced to create gaps 250 therebetween of equal size(recognizing that the line connector bar 178 interrupts the equidistantspacing on the L-conductor 174). As shown, two support blocks 242 arelocated on either side of the line connector bar 178 on the L-conductor174 and similarly arranged support blocks (not shown) are located on theL-support 222.

The insulating rope 246 is wrapped around the L-conductor 174 and theL-support 222, guided by the support blocks 242. The insulating rope 246may be the same as the insulating rope 78 described above with respectto FIG. 8 . The insulating rope 174 is wrapped along the gaps 250between the adjacent support blocks 242 on the L-conductor 174, over thecurved profile located adjacent the shoulder 198 and around theinsulator 238, and along the gaps between the adjacent support blocks onthe L-support 222. The insulating rope 246 encircles the L-conductor 174and L-support 222 multiple times, thereby coupling the L-conductor 174to the L-support 222. As shown, the insulating rope 246 wraps around sixtimes, once along each gap 250 adjacent to a support block 242. With theinsulating rope 246 installed, the line coil ends 170 and L-conductor174 are mechanically supported by the L-support 222 that is secured tothe star coil ends 190.

FIG. 17 illustrates an inner face of the L-conductor 174 or theL-support 222 (inner referring to inside of the “L” shape), as bothelements can share the same design. The inner face of the L-conductor174 is in a facing relationship with the inner face of the L-support 222such that the inner faces are adjacent to one another, separated only bythe insulator 238 therebetween. As shown, the inner face includesdepressions or blind holes 262 such as shallow flat bottom holes thatare sized (e.g., diameter, depth, quantity) to ensure that the remainingcross-sectional area for the L-conductor 174 is sufficient to carry therequired rotor line current. Flat bottom holes (as opposed to, forexample, tapered holes), avoid a stress concentration at the centerpoint of the hole which may otherwise result in a stress fracture. Whenthe felt insulator 238 is impregnated with resin (e.g., polyester,epoxy, silicone), it expands into the flat bottom holes 262. When theresin is cured, the resin and felt, in combination with the shallow,flat bottom holes 262, provide increased mechanical strength to theinterface between the L-conductor 174 and the L-support 222 while stillmaintaining a high voltage insulation level. The flat bottom holes 262may be machined or drilled using an endmill bit or a 180-degreecounterbore drill.

FIG. 18 illustrates additional mechanical supports 270 being provided onopposite sides of the line and star coils 170, 190. AdditionalL-supports 274 a, 274 b are secured (e.g., brazed, soldered, welded) tothe opposing sides of the line and star coils 170, 190 (opposite thesides to which the L-conductor and L-support discussed above aresecured) to provide additional mechanical strength and rigidity to theconnection. Each of these L-support pairings includes two L-supports 274a, 274 b and does not include an L-conductor, as these supports 274 a,274 b are not required for any current carrying capabilities. TheL-supports 274 a, 274 b include insulating rope 278 and support blocks282, utilizing the same connection as described above with respect tothe connection between the L-conductor 174 and the L-support 222 shownin FIG. 16 .

FIG. 19 illustrates that the line connector bar 178 is mechanicallysupported by a support ring 310. As shown, the connection between theline connector bar 178 and the support ring 310 is an indirectconnection, with fish plates 314 a, 314 b connecting the line connectorbar 178 to the support ring 310 (e.g., to a spoke of the support ringextending radially at a common circumferential position with the lineconnector bar 178).

In order to withstand centrifugal acceleration and deceleration forces,the line connector bar 178 is supported both radially as well as axiallyby the support ring 310. The support ring 310 is a ring (e.g., a carbonsteel ring) positioned adjacent to the coils 42, 46, though having anouter diameter less than the inner diameter of the coils 42, 46 suchthat the support ring 310 is located radially within the ends of thecoils 42, 46. The support ring 310 includes axial cutouts 322 whichallow for airflow therethrough for cooling the motor. Axially drilledholes 326 extend through the support ring 310 adjacent to the outerperiphery (outside diameter) of the support ring 310, spaced apart fromone another about the circumference of the ring 310. The axial holes 326facilitate the fitment of temporary pins used in the winding process.After the winding process is complete, the holes 326 are used forbalancing the rotor 34. To balance the rotor 34, balancing weights areadded to the axial holes 326. Pre-drilling the holes 326 beforeinstallation facilitates their use for balancing as the assembledsupport ring 310 lacks the space for drilling the holes 326.

Additionally, the support ring 310 includes a plurality of features forfacilitating assembly of the fish plates 314 a, 314 b to the supportring 310. The support ring 310 includes a peripheral cutout 334 at theoutside diameter of the support ring 310. The peripheral cutout 334provides space for a drill bit to reach the mounting portion for theline connector bar 178 and to facilitate drilling the mounting holes forthe fish plates 314 a, 314 b. Further, the mounting portion for the lineconnector bar has two slightly oversized holes 342 to allow foralignment of the fish plates 314 a, 314 b.

The line connector bar 178 is fastened (e.g., bolted) to the supportring 310 via the fish plates 314 a, 314 b. As shown in FIG. 19 , twofish plates 314 a, 314 b (one on opposing sides of the line connectorbar 178) bridge an axial gap 350 between the line connector bar and thesupport ring 310, with a first plurality of fasteners 354 (e.g., bolts)extending through apertures in the fish plates 314 a, 314 b and the lineconnector bar 178 and a second plurality of fasteners 358 (e.g., bolts)extending through apertures in the fish plates 314 a, 314 b and thesupport ring 310. The support ring 310 is coupled (e.g., heat shrunkfit) to the shaft of the rotor and is therefore contacting the shaftboth electrically and mechanically. It is advantageous for the lineconnector bar 178 to be electrically insulated from the shaft. As such,the fish plates 314 a, 314 b are manufactured from a glass mat orlaminate saturated and cured with resin (e.g., glass mat with polyesterresin, glass laminate with epoxy resin). The fish plates 314 a, 314 band connections are repeated for each line coil.

FIG. 20 illustrates that the line connector bar 178 is bolted to therotor leads 166 by a machined connector block 366. The machinedconnector block 366 is manufactured from copper or copper alloy (e.g.,brass, bronze, chrome copper zirconium (CuCrZr), beryllium copper(CuBe)) and is sized to achieve the required current carrying capacitybased on the rotor line current while still fitting onto the lineconnector bar 178. The machined connector block 366 is secured (e.g.,brazed, soldered, welded) to the line connector bar 178. A cable lug 370is bolted to the machined connector block 366 and the machined connectorblock 366 is sized large enough to provide this connection. Theconnector block 366 is mounted at an offset location (off-centercircumferentially - see FIG. 19 also) relative to the line connectorbar, as shown by distance 378 on FIG. 20 . This ensures correctalignment of the rotor leads 166 with the line connector bar 178,reduces bending and stresses on the rotor leads 166, and avoids pinchingthe rotor leads 166 as they exit the shaft holes. Two chamfered edges374 on the machined connector block 366 allow for unrestricted fitmentof the cable lug 370 and interchangeability of the lead direction.

What is claimed is:
 1. A rotor of a wound rotor motor/generator, the rotor comprising: a plurality of rotor windings including a line rotor coil and a star rotor coil; an L-conductor having an L-shaped profile and coupled to the line rotor coil such that a portion of the L-conductor extends from the line rotor coil toward the star rotor coil; a line connector bar coupling the L-conductor to a rotor lead such that the line rotor coil is electrically coupled to the rotor lead; an L-support having an L-shaped profile and coupled to the star rotor coil such that a portion of the L-support extends from the star rotor coil toward the line rotor coil; an insulator positioned between the L-conductor and the L-support to electrically insulate the L-support from the L-conductor; and an insulating rope coupling the L-conductor to the L-support.
 2. The rotor of claim 1, wherein the L-conductor includes support blocks that define a plurality of gaps therebetween, wherein the insulating rope is positioned within the plurality of gaps.
 3. The rotor of claim 1, further comprising a support ring positioned radially within the plurality of rotor windings, the support ring coupled to the line connector bar to support the line connector bar during acceleration of the rotor.
 4. The rotor of claim 3, further comprising a fish plate coupled to the support ring and coupled to the line connector bar, such that the support ring is indirectly coupled to the line connector bar via the fish plate.
 5. The rotor of claim 1, wherein the L-conductor includes a first portion that is coupled to the line rotor coil, wherein the portion of the L-conductor that extends from the line rotor coil toward the star rotor coil is a second portion of the L-conductor, and wherein the second portion of the L-conductor extends transverse to the first portion of the L-conductor to define the L-shaped profile of the L-conductor.
 6. The rotor of claim 5, wherein the L-support includes a first portion that is coupled to the star rotor coil, wherein the portion of the L-support that extends from the star rotor coil toward the line rotor coil is a second portion of the L-support, and wherein the second portion of the L-support extends transverse to the first portion of the L-support to define the L-shaped profile of the L-support.
 7. The rotor of claim 6, wherein the second portion of the L-conductor is axially aligned with the first portion of the L-support and the second portion of the L-support is axially aligned with the first portion of the L-conductor such that the L-conductor is nested with the L-support.
 8. The rotor of claim 1, wherein the plurality of rotor windings includes a plurality of top coils and a plurality of bottom coils, the bottom coils being located radially within the top coils, wherein both of the line rotor coil and star rotor coil are top coils.
 9. The rotor of claim 1, wherein the L-conductor is soldered, brazed, or welded to the line rotor coil and wherein the L-support is soldered, brazed, or welded to the star rotor coil.
 10. The rotor of claim 1, wherein the L-conductor and the L-support are positioned between the line rotor coil and the star rotor coil, the rotor further comprising a first plurality of additional L-supports coupled to the line rotor coil opposite the L-conductor, the rotor further comprising a second plurality of additional L-supports coupled to the star rotor coil opposite the L-support, such that the first and second pluralities of additional L-supports provide additional mechanical strength and rigidity to the rotor. 